Many scientists saw climate change as a distant threat for decades. Now we know it was wrong to say. For example, this summer a European heat wave reached the Arctic driving temperatures through much of the Far North in the 1980s and melted some 40 billion tons of the Greenland ice sheet . If a scientist had proposed at the beginning of the 1990's that within 25 years, a single wave of heat would raise sea levels measurably, heat the Arctic at an estimated two one-hundredths of an inch, and bring to Europe Sahara-like temperatures, the prediction would have been ignored as a warning. But now, a lot of worst-case scenarios from that time are reality.
In 1990, in its first report, the Intergovernmental Panel on Climate Change said that climate change would arrive at a stable pace, that methane-powered permafrost of the Arctic would not thaw and that the ice sheets of the Antarctic were stable. Based on the evaluation of the committee on climate change, analysts predicted that the economic hit would be tiny , allowing more opportunities to reduce emissions in an aggressive manner and create climate change resilience.
All these predictions, as we know now, have been entirely wrong. This leads you to question whether further temperature rise, unfortunate as they are, could still be understated. How bad things are going to get?
Ultimately, the committee on climate change seems to have been shaken by the severity of the climate problem. The organization last year detailed  the exceptional difficulty of restricting warming over the next 80 years to 1.5 degrees Celsius. Alarmingly, we are heading to warming at least 5.4 degrees Fahrenheit, according to a different United Nations study. That would be damaging to economies and ecosystems almost unimaginably. This dose of reality unfortunately happens after more than 30 years since climate change has become a major issue.
An American Scientist, Dr. Wallace S. Broecker published the paper "Climate Change: Are we on the Brink of a Pronounced Global Warming?" in 1975. He estimated that carbon dioxide emissions would substantially increase earth's temperature in the 21st century. It is seen now as prophecy, but Dr. Broecker was considered an outlier at that time.
In 2002, in a report titled as, "Abrupt Climate Change: Inevitable Surprises", the National Academies accepted the fact that extreme weather events were in fact "a paradigm shift". "The hemisphere has been affected on a number of occasions repeatedly by large, abrupt climate changes in global regions, as numerous paleoclimate data demonstrate," the report said. The National Academies study also indicated that politicians and analysts have not yet considered the implications of such future rapid changes. And even now, 17 years later, many People are either unaware or unconvinced of it. As the sea-level rises, they are heating at an unprecedented pace as compared to only 5 years ago. It is really bad news. First of all, the hotter climate means more intense hurricanes and losses of aquatic life, but it also suggests that the planet is more responsive than previously thought of rising carbon dioxide emissions.
Even though researchers actually have yet to assess the impact of greenhouse gas emissions that we continue to emit in the air, their estimates are extremely grim. It is already here, and it's going to get worse. Much worse.